John

John the Ripper (often referred to as John) is an open-source password cracking tool used to test the strength of passwords by performing brute-force and dictionary attacks. It is designed to detect weak passwords by trying many possible combinations or known patterns (like words from a dictionary). John supports various cryptographic hash algorithms, including those used in Unix, Windows, and other systems. It is widely used by security professionals, penetration testers, and attackers to identify vulnerable password security.

Installation :

sudo apt install john

---

Usage: john [OPTIONS] [PASSWORD-FILES]

--help                     Print usage summary
--single[=SECTION[,..]]    "Single crack" mode, using default or named rules
--single=:rule[,..]        Same, using "immediate" rule(s)
--single-seed=WORD[,WORD]  Add static seed word(s) for all salts in single mode
--single-wordlist=FILE     *Short* wordlist with static seed words/morphemes
--single-user-seed=FILE    Wordlist with seeds per username (user:password[s]
                           format)
--single-pair-max=N        Override max. number of word pairs generated (6)
--no-single-pair           Disable single word pair generation
--[no-]single-retest-guess Override config for SingleRetestGuess
--wordlist[=FILE] --stdin  Wordlist mode, read words from FILE or stdin
                  --pipe   like --stdin, but bulk reads, and allows rules
--rules[=SECTION[,..]]     Enable word mangling rules (for wordlist or PRINCE
                           modes), using default or named rules
--rules=:rule[;..]]        Same, using "immediate" rule(s)
--rules-stack=SECTION[,..] Stacked rules, applied after regular rules or to
                           modes that otherwise don't support rules
--rules-stack=:rule[;..]   Same, using "immediate" rule(s)
--rules-skip-nop           Skip any NOP ":" rules (you already ran w/o rules)
--loopback[=FILE]          Like --wordlist, but extract words from a .pot file
--mem-file-size=SIZE       Size threshold for wordlist preload (default 2048 MB)
--dupe-suppression         Suppress all dupes in wordlist (and force preload)
--incremental[=MODE]       "Incremental" mode [using section MODE]
--incremental-charcount=N  Override CharCount for incremental mode
--external=MODE            External mode or word filter
--mask[=MASK]              Mask mode using MASK (or default from john.conf)
--markov[=OPTIONS]         "Markov" mode (see doc/MARKOV)
--mkv-stats=FILE           "Markov" stats file
--prince[=FILE]            PRINCE mode, read words from FILE
--prince-loopback[=FILE]   Fetch words from a .pot file
--prince-elem-cnt-min=N    Minimum number of elements per chain (1)
--prince-elem-cnt-max=[-]N Maximum number of elements per chain (negative N is
                           relative to word length) (8)
--prince-skip=N            Initial skip
--prince-limit=N           Limit number of candidates generated
--prince-wl-dist-len       Calculate length distribution from wordlist
--prince-wl-max=N          Load only N words from input wordlist
--prince-case-permute      Permute case of first letter
--prince-mmap              Memory-map infile (not available with case permute)
--prince-keyspace          Just show total keyspace that would be produced
                           (disregarding skip and limit)
--subsets[=CHARSET]        "Subsets" mode (see doc/SUBSETS)
--subsets-required=N       The N first characters of "subsets" charset are
                           the "required set"
--subsets-min-diff=N       Minimum unique characters in subset
--subsets-max-diff=[-]N    Maximum unique characters in subset (negative N is
                           relative to word length)
--subsets-prefer-short     Prefer shorter candidates over smaller subsets
--subsets-prefer-small     Prefer smaller subsets over shorter candidates
--make-charset=FILE        Make a charset, FILE will be overwritten
--stdout[=LENGTH]          Just output candidate passwords [cut at LENGTH]
--session=NAME             Give a new session the NAME
--status[=NAME]            Print status of a session [called NAME]
--restore[=NAME]           Restore an interrupted session [called NAME]
--[no-]crack-status        Emit a status line whenever a password is cracked
--progress-every=N         Emit a status line every N seconds
--show[=left]              Show cracked passwords [if =left, then uncracked]
--show=formats             Show information about hashes in a file (JSON)
--show=invalid             Show lines that are not valid for selected format(s)
--test[=TIME]              Run tests and benchmarks for TIME seconds each
                           (if TIME is explicitly 0, test w/o benchmark)
--stress-test[=TIME]       Loop self tests forever
--test-full=LEVEL          Run more thorough self-tests
--no-mask                  Used with --test for alternate benchmark w/o mask
--skip-self-tests          Skip self tests
--users=[-]LOGIN|UID[,..]  [Do not] load this (these) user(s) only
--groups=[-]GID[,..]       Load users [not] of this (these) group(s) only
--shells=[-]SHELL[,..]     Load users with[out] this (these) shell(s) only
--salts=[-]COUNT[:MAX]     Load salts with[out] COUNT [to MAX] hashes, or
--salts=#M[-N]             Load M [to N] most populated salts
--costs=[-]C[:M][,...]     Load salts with[out] cost value Cn [to Mn]. For
                           tunable cost parameters, see doc/OPTIONS
--fork=N                   Fork N processes
--node=MIN[-MAX]/TOTAL     This node's number range out of TOTAL count
--save-memory=LEVEL        Enable memory saving, at LEVEL 1..3
--log-stderr               Log to screen instead of file
--verbosity=N              Change verbosity (1-5 or 6 for debug, default 3)
--no-log                   Disables creation and writing to john.log file
--bare-always-valid=Y      Treat bare hashes as valid (Y/N)
--catch-up=NAME            Catch up with existing (paused) session NAME
--config=FILE              Use FILE instead of john.conf or john.ini
--encoding=NAME            Input encoding (eg. UTF-8, ISO-8859-1). See also
                           doc/ENCODINGS.
--input-encoding=NAME      Input encoding (alias for --encoding)
--internal-codepage=NAME   Codepage used in rules/masks (see doc/ENCODINGS)
--target-encoding=NAME     Output encoding (used by format)
--force-tty                Set up terminal for reading keystrokes even if we're
                           not the foreground process
--field-separator-char=C   Use 'C' instead of the ':' in input and pot files
--[no-]keep-guessing       Try finding plaintext collisions
--list=WHAT                List capabilities, see --list=help or doc/OPTIONS
--length=N                 Shortcut for --min-len=N --max-len=N
--min-length=N             Request a minimum candidate length in bytes
--max-length=N             Request a maximum candidate length in bytes
--max-candidates=[-]N      Gracefully exit after this many candidates tried.
                           (if negative, reset count on each crack)
--max-run-time=[-]N        Gracefully exit after this many seconds (if negative,
                           reset timer on each crack)
--mkpc=N                   Request a lower max. keys per crypt
--no-loader-dupecheck      Disable the dupe checking when loading hashes
--pot=NAME                 Pot file to use
--regen-lost-salts=N       Brute force unknown salts (see doc/OPTIONS)
--reject-printable         Reject printable binaries
--tune=HOW                 Tuning options (auto/report/N)
--subformat=FORMAT         Pick a benchmark format for --format=crypt
--format=[NAME|CLASS][,..] Force hash of type NAME. The supported formats can
                           be seen with --list=formats and --list=subformats.
                           See also doc/OPTIONS for more advanced selection of
                           format(s), including using classes and wildcards.

Examples

sudo john --wordlist=rockyou.txt hashfile.txt
john --show hashfile.txt